Can Iran Close The World's Most Important Oil Route?

A member of Iran's navy participates in a drill on Dec. 28, 2011, in the Sea of Oman. Tehran is threatening to close the strategic Strait of Hormuz at the mouth of the Persian Gulf, in retaliation for new sanctions by the West. (AP)

As tensions rise between Iran and the West, Tehran has threatened to block the Strait of Hormuz, a transit route for one-fifth of the world's oil. Is it more than an empty threat?

"The simple answer is: Yes, they can block it," Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said on CBS's Face the Nation on Jan. 8.

"They've invested in capabilities that for a short period of time block the Strait of Hormuz," he said.

'A Poor Man's Navy'

Among those capabilities: laying mines.

"Mines are sort of a poor man's navy," says Michael Connell, who runs the Iranian studies program at the Center for Naval Analyses, a Washington think tank. "Anybody can buy mines."

But they are tricky, he adds.

"If you just throw a few in the water, it makes things complex: Because you can just throw a few in the water, and you have to sweep for them before you let ships go through," he says.

And that means mines are a cheap and easy way to wreak havoc on — and even close — the strait, says Norman Polmar, who has written widely on U.S. and foreign navies.

"The question is how long," he says. "It might be a day. It might be a week. It might be a couple of weeks."

A Flash Point In The 1980s

Iran has never laid mines at the Strait of Hormuz, but it did place mines inside the Persian Gulf during its war with Iraq in the 1980s. A U.S. Navy ship was damaged. The U.S. responded by attacking Iranian aircraft and ships.

The U.S. has several options if Iran tried to close the Strait of Hormuz now.

"Laying mines is an act of war, so it would be up to our nation's leaders to determine how aggressive our response would be," says retired Adm. Tim Keating, who commanded the U.S. 5th Fleet in Bahrain during the run-up to the Iraq war.

He says the best way to defeat mines is to spot them.

"We'd likely know immediately, if not very shortly thereafter, which ships did it, where they're coming from, where they're going back to," Keating says.

The surveillance includes sophisticated drone aircraft — and a sophisticated mammal.

"We've got dolphins. ... They are astounding in their ability to detect underwater objects," he says.

The U.S. Navy sent dolphins to the Persian Gulf as part of the American invasion force in Iraq. Keating confirms they were "present in the theater," but he declines to talk about whether the animals were used or not.

Iranian 'Fast Boats' Pose A Risk

Mines might be the cheapest way for the Iranians to close the strait. Its ships and aircraft are no match for the American military might in the region.

Transcript

We just heard about why Iran might want to close the Strait of Hormuz. Now, NPR Pentagon correspondent Tom Bowman looks at whether or not they could actually pull it off and how.

TOM BOWMAN, BYLINE: First, things first. Can Iran close the world's most important oil route?

GENERAL MARTIN DEMPSEY: The simple answer is, yes, they can block it.

BOWMAN: That's General Martin Dempsey, chairman of the Joint Chiefs of Staff, on CBS's "Face the Nation."

DEMPSEY: They've invested in capabilities that could, in fact, for a period of time block the Strait of Hormuz.

BOWMAN: Capabilities that play to Iran's strengths since its ships and aircraft are no match for the American military. One tactic: Iran could lay mines.

MICHAEL CONNELL: Mines are sort of a poor man's navy. I mean, anybody can buy mines.

BOWMAN: That's Michael Connell. He runs the Iranian studies program at the Center for Naval Analyses, a Washington think tank.

CONNELL: Mines, you know, they are tricky things. If you just throw a few in the water, it makes things complex because then you have to go out and sweep for them and make sure the channels are clear before you start sending vessels through.

BOWMAN: Meaning mines are a cheap and easy way to wreak havoc.

NORMAN POLMAR: It would close the strait.

BOWMAN: Norman Polmar writes on U.S. and foreign navies.

POLMAR: For how long, that's the big question. It might be a day. It might be a week. It might be a couple of weeks.

BOWMAN: Iran has never laid mines at the Strait of Hormuz, but it has placed mines inside the Persian Gulf. During its war with Iraq in the 1980s, a U.S. Navy ship hit a mine and was damaged. The U.S. responded by attacking Iranian aircraft and ships. The U.S. has several options if Iran tries to close the Strait of Hormuz now.

ADMIRAL TIM KEATING: You know, laying mines is an act of war, so it would be up to our nation's leaders to determine just how aggressive our response would be.

BOWMAN: That's retired Admiral Tim Keating, who commanded the U.S. 5th Fleet in Bahrain during the run-up to the Iraq war. He says the best way to defeat mines is to find the mines and identify the mine layers.

KEATING: We'd likely know immediately, if not very shortly thereafter, which ships were doing it, where they were coming from, where they're going back to.

BOWMAN: The surveillance includes sophisticated drone aircraft and a sophisticated mammal.

KEATING: We've got dolphins. And how lovable is Flipper? But they are astounding in their ability to detect underwater objects.

BOWMAN: Dolphins were sent to the Persian Gulf as part of the American invasion force in Iraq.

KEATING: I'd rather not talk about whether we used them or not. They were present in theater.

BOWMAN: But you can't say whether you used them or not.

KEATING: I'd rather not.

BOWMAN: Mines might be the cheapest way for the Iranians to close the strait. Another possibility says Norman Polmar, the naval expert, Iran's fast boats, its small and lethal naval vessels. These boats have emerged as a key weapon for the Iranians. During war games, they have developed dozens of them in the Persian Gulf, mounting mock attacks on target ships. Again, Admiral Keating.

KEATING: Fifty of anything coming at you is a bit of a challenge.

BOWMAN: And last year there were reports that the Iranians upgraded the boats, possibly with better torpedoes. Still, Iran may not have to disable an oil tanker, let alone close the Strait of Hormuz, to hurt the United States. Just by talking tough, Iran can drive up the cost of oil. Tom Bowman, NPR News, Washington. Transcript provided by NPR, Copyright NPR.